Girls surpass boys in verbal achievement, but after grade school fall progressively behind boys in mathematical achievement. The origins of sex differences in mathematical vs. verbal achievement are analyzed in terms of girls' greater tendency to exhibit learned helplessness in the face of failure. In general, girls tend to attribute their academic failures to a lack of ablility and to show impaired performance, decreased persistence, and task avoidance when failure occurs--even in areas of demonstrated competence. Boys, in contrast, attribute their failure to a lack of effort and show improved performance following failure. Throughout the school years, the acquisition and performance of new math skills produce far more floundering or failure than do the more gradual increments in most verbal skills, thus providing more opportunity for girls' helplessness to impair acquisition and performance of math skills, approach to math tasks, and perception of competence in math. Three related lines of research are proposed. The first examines girls' greater debilitation by failure on tasks that have involved an initial period of confusion with new concepts during acquisition (as in math)--despite mastery of the skill in question. The second examines the nature of the performance required on math tasks (achievement tests) versus verbal tasks and demonstrates that the task requirements of math are the very ones that are most disrupted by helplessness when failure occurs. The third, combining field and laboratory research, examines the pattern of teachers' classroom feedback in math vs. verbal areas that leads to greater attractiveness of math for boys given their achievement orientations, but decreased attractiveness for girls given theirs. In summary, it is proposed that the failure or stumbling involved in acquiring math skills combines with girls' inability to cope with negative outcomes to produce impaired performance and avoidance of math.